Field of the Invention
The present invention relates to a wireless power supply system in which a power transmitting apparatus wirelessly supplies power to a power receiving apparatus assigned.
Description of the Related Art
Four systems are known as a system of supplying power contactlessly (wirelessly). Specifically, they are an electromagnetic induction system, a magnetic field resonance system, an electronic filed coupling system and a radio wave reception system. In recent years, among the four systems, the magnetic field resonance system capable of compatibly achieving sufficient power that can be transmitted and a long power transmitting distance is drawing attention. In the magnetic field resonance system, a one-to-N power supply system in which a power transmitting apparatus transmits the power to a plurality of power receiving apparatuses utilizing the power transmitting distance is proposed (for instance, Japanese Patent Application Laid-Open No. 2009-136132).
In the technology described in Japanese Patent Application Laid-Open No. 2009-136132, fixed pulse signals are transmitted in a standby mode in the case that the power transmitting apparatus is not supplying the power and whether or not a power receiving apparatus approaches the power transmitting apparatus within several meters is searched. When the power receiving apparatus sends its own intrinsic ID to the power transmitting apparatus, the power transmitting apparatus discriminates whether the power receiving apparatus is the power receiving apparatus of a power supply target. In the case of the power receiving apparatus of the power supply target, the power transmitting apparatus sends supply power to the power receiving apparatus. At the time, the power transmitting apparatus can send an intrinsic code to the power receiving apparatus in order to individually receive a charging amount, a state of an apparatus or the like from the power receiving apparatus.
However, in the case that the plurality of power transmitting apparatuses of the same power transmitting frequency are present, a problem arises that receiving power declines since interference occurs among electromagnetic waves output from the individual power transmitting apparatuses when the power receiving apparatus simultaneously receives wireless power supply from the plurality of power transmitting apparatuses.
It is an object of the present invention to prevent the receiving power of the power receiving apparatus from declining when the plurality of power transmitting apparatuses wirelessly supply the power to the plurality of power receiving apparatuses.